Another quick point forgot to add re OM. My own research into MLC is that MLCer views the spouse as the enemy - the reason for why the feel like they do and the barrier to them achieving happiness. But we knew that already. They want to hate the spouse.
The OM is her person to confide in - her hero. Who will validate those feelings W has about me and offer advice (usually in his benefit). By telling W no contact etc etc or rubbishing OM, I am strengthening their bond and view that I don't understand her and that I am trying to break up their friendship - i.e. ruin W happiness.
By championing him then maybe (and s alight maybe) this will help W see me differently. That I am not the enemy trying to make her unhappy/ruin her fantasy and in fact there to support her as well.